(ET) steering wheel center cap

[tbamc <tbamc gbta net>]

I'm trying to find a center/logo cap for the steering wheel of my 12M.  
Another lister sent me the smaller of the 2 sizes he had.  It seems to 
be maybe 1/16" to 1/8" too large to fit.  The parts list on ET.com shows 
the 12M and the 20 to be the same, while the 12, 12S and 15 are the 
same.  The price list shows a THIRD option but doesn't say what it fits 
(E8 or 10?).  As I REALLY don't want to break this trying to force it 
in, can anyone shed some light on this?
Thanks.
Thon